Methods and surgical instruments for abrading tissue are known in the art. Typically, surgical abrading instruments are sized and shaped to be inserted into the body through a small opening in the flesh, as would be used in arthroscopic surgical procedures. U.S. Pat. No. 4,842,578 to Johnson et al. discloses a surgical abrading instrument that includes the combination of a distally, side-supported inner drive tube carrying on its end an abrading element, and a fixed bearing tube surrounding the inner tube and providing at a bearing region the distal support for the inner tube. A distal extension of the bearing tube provides a sheath for a portion of the abrading element. A vacuum passage communicates proximally from the region of the abrading element, past the bearing region, to a proximal vacuum connection. During driving of the tube and drawing of suction through the vacuum connection, particles dislodged by the driven, side-supported abrading element may be drawn past the bearing region and out of the instrument.
Once inserted into the body, the abrader is used for various surgical procedures that involve abrading, cutting, or shaping soft tissue and hard tissue, such as bone, cartilage, or ligament, by use of a rotating abrading head secured to a rotatable inner tube. As the tissue is being abraded, debris is generally drawn by suction through the lumen of the rotatable inner tube, along with physiological and irrigation fluid. In the example disclosed in the '578 patent, the suction port is located immediately proximal to the abrading head, and a bearing is located proximal to the head and the suction port to allow maximum exposure of the abrading head at the distal tip of the instrument. According to the '578 patent, the debris flows past the abrading head and enters the immediately adjacent suction port between the inner tube and the outer tube. During the abrading procedure, tissue may wrap around the instrument and block the suction port.
Another approach is provided in U.S. Pat. No. 6,053,923 issued to Veca et al. The abrading instrument of the '923 patent has openings in the side of the rotating inner tube, which align with a single suction port in the side of the outer tubular member. The openings in the inner tube are disposed proximally to the abrading head. Thus, surgical debris is drawn back from the abrading head along the outside of the bearing area, and then into the suction port of the outer tube, through the suction openings of the inner tube, and out of the instrument. A self-cleaning mechanism is formed by sharpening the edges of the two openings, which pass at close tolerances during rotation of the inner tube within the outer tube, to impart a tissue-cutting action as the edges of the openings pass one another.
A surgeon using the abrading apparatus disclosed in the '923 patent must be careful, however, to avoid cutting tissue adjacent the surgical site with the sharpened edges of the self-cleaning mechanism. Further, tight tolerances between the inner and outer tubes necessary to provide an effective tissue-cutting action also render the instrument vulnerable to binding between the inner and outer tubes during an abrading operation. In addition, as the inner tube rotates within the outer tube, the suction flow through the ports in the outer and inner tubes becomes at least partially blocked or impeded by portions of the inner tube cyclically closing off the openings as the inner tube rotates. Thus, an improved design for avoiding aspiration of tissue through abrading apparatus bearings and improving aspiration flow is desired.
Accordingly, it would be desirable to provide a surgical abrading instrument that reduces blockage and eliminates the need for repeatedly clearing the abrader. There also is a need for a method for conducting a surgical abrading procedure with increased efficiency and reduced cost and time.